And Testable Design Solution — Digital Systems Testing

In test mode, all flip-flops are connected into a long shift register (a Scan Chain). The Benefit:

The fundamental dilemma is that normal functional operation and testing mode have contradictory requirements. Functionality seeks to minimise pins, hide internal states, and optimise speed. Testing seeks maximum access, full visibility, and deterministic control. digital systems testing and testable design solution

One of the biggest hurdles in testing is (seeing what’s happening inside) and controllability (setting internal states). In test mode, all flip-flops are connected into